Compact temperature stabilized crystal oscillator
AssigneeLocus LP
InventorThomas P. Blandino
Life of this patent
Estimating the term…
Abstract
A compact temperature controlled crystal oscillator employs a high conductivity heat spreader bonded to one side of a printed circuit board into the crystal. Heaters are arranged at edges of the circuit board and a temperature sensor for the temperature regulation circuitry is centered in the circuit board with components of high thermal sensitivity being placed in zones closer to the temperature sensor. An operating temperature of the heat spreader is selected by measuring multiple operating temperatures at different ambient temperatures and picking an operating temperature that causes a least absolute frequency deviation.
Claims11
A temperature stabilized crystal oscillator comprising:
- a circuit board;
- at least one heater mounted to the circuit board;
- heater control circuitry including a temperature sensor mounted to the circuit board and communicating with the heater to control it to provide a predetermined temperature at the temperature sensor;
- a tuned crystal;
- crystal driving circuitry mounted to the circuit board to electrically drive the tuned crystal at a predetermined frequency;
- and
- a solid heat spreader in thermal communication with the tuned crystal, the circuit board, the heater, the temperature sensor, and at least a portion of the crystal driving circuitry.
A method of trimming a temperature stabilized crystal oscillator for operating in an environmental temperature range and having:
- a circuit board;
- at least one heater mounted to the circuit board;
- heater control circuitry including a temperature sensor mounted to the circuit board and communicating with the heater to control the heater to provide a predetermined temperature at the temperature sensor;
- a tuned crystal;
- crystal driving circuitry mounted to the circuit board to electrically drive the tuned crystal at a predetermined frequency;
- and
- a solid heat spreader attached to the tuned crystal and positioned to abut the circuit board in thermal communication with the heater, at least a portion of the crystal driving circuitry, and the temperature sensor, the method comprising the steps of:
- (a) identifying a centered temperature to which the heat spreader will be regulated;
- (b) exposing the oscillator to a mean environmental temperature of the temperature range and measuring frequencies at a plurality of trial regulation temperatures about the nominal centered temperature;
- (c) fitting a curve to the measured frequencies and trial regulation temperatures;
- and
- (d) selecting a regulation temperature from among the plurality of trial regulation temperatures in a region of minimized slope in the fitted curve.
A method of trimming a temperature stabilized crystal oscillator for operating in an environmental temperature range and having:
- a circuit board;
- at least one heater mounted to the circuit board;
- heater control circuitry including a temperature sensor mounted to the circuit board and communicating with the heater to control the heater to provide a predetermined temperature at the temperature sensor;
- a tuned crystal;
- crystal driving circuitry mounted to the circuit board to electrically drive the tuned crystal at a predetermined frequency;
- and
- a solid heat spreader attached to the tuned crystal and positioned to abut the circuit board in thermal communication with the heater, at least a portion of the crystal driving circuitry, and the temperature sensor, the method comprising the steps of:
- (a) identifying a centered temperature to which the heat spreader may be regulated;
- (b) exposing the oscillator to a first environmental temperature of the temperature range and measuring first frequencies at a plurality of regulation temperatures about the centered temperature;
- (c) exposing the oscillator to at least one second environmental temperature of the temperature range measuring second frequencies at the plurality of trial regulation temperatures about the centered temperature;
- and
- (d) selecting a final regulation temperature from among the plurality of trial regulation temperatures to minimize the difference between the corresponding first and second frequencies for the selected final regulation temperature.
Dependencies are inferred from the claim text.